Stabilized isocyanate composition

ABSTRACT

STABILIZED ORGANIC ISOCYANATE COMPOSITION CONTAINING AN ORGANIC ESTER OR ESTERS OF ISOCYANIC ACID SUCH AS XYLENE, W,W&#39;&#39;-DISOCYANATE IN COMBINATION WITH A STABILIZER WHICH IS ONE OR MORE OF THE ACYL ISOCYANATES ENCOMPASSES BY THE FORMULA   R1-CX-NCY   R2(CX-NCY)2   R1-SO2-NCO   WHEREIN EACH OF X AND Y IS O OR S, R1 IS AN ALKYL, ARALKYL, ARYL, ALL OF WHICH MAY BE SUBSTITUTED BY ONE OR MORE HALOGENS, -NO2, -CH, ALKYL OR ALOXY, AND R2 IS A BIVALENT HYDROCARBON RESIDUE, THE AMOUNT OF THE ACYL ISOCYANATE OR ACYL ISOCYANATES BEING ABOUT 0.001 TO 1.0 PERCENT INVENTION ALSO INVLOVES A METHOD OF STABILIZTHE PERCENT INVENTION ALSO INVOLVES A METHOD OF STABILIZING AN ORGANIC ISOCYANATE ESTER BY INCLOPORATING THE AFOREMENTIONED STABILIZER OR STABILIZERS THEREIN.

United States Patent 3,743,665 STABILIZED ISOCYANATE COMPOSITION Kenji Naito, Katsuhiko Ogino, and Hiroshi Okudo, Toyonaka, Michio Tanaka, Suita, Yoshio Kamatam, Osaka, Hiroshi Mukai, Toyonaka, and Tatsuro Takeuchi, Suita, Japan, assignors to Takeda Chemical Industries, Ltd., Osaka, Japan No Drawing. Filed June 19, 1970, Ser. No. 47,913 Int. Cl. C07c 119/04 US. Cl. 260-453 SP 17 Clauns ABSTRACT OF THE DISCLOSURE Stabilized organic isocyanate composition containing an organic ester or esters of isocyanic acid such as xylene, w,w-diisocyanate in combination with a stabilizer which is one or more of the acyl isocyanates encompassed by the formula R -CX--NCY R (CXNCY) z R SO -NCO wherein each of X and Y is O or S, R is an alkyl, aralkyl, aryl, all of which may be substituted by one or more halogens, NO -CN, alkyl or alkoxy, and R is a bivalent hydrocarbon residue, the amount of the acyl isocyanate or acyl isocyanates being about 0.001 to 1.0 percent by weight relative to the organic isocyanate ester. The present invention also involves a method of stabilizing an organic isocyanate ester by incorporating the aforementioned stabilizer or stabilizers therein.

The present invention relates to a stabilized isocyanate composition. More concretely, the present invention relates to an organic isocyanate composition stabilized against undesirable polymerization and coloration.

In the present specification as well as in claims, the term organic isocyanate it to be construed as meaning organic ester or esters of isocyanic acid, the ester having the structure of an ester between HNCO and an alcoholic or phenolic hydroxyl compound, and the ester may have one or more NCO groups in its molecule. Organic isocyanates are unstable because of the high reactivity of their isocyanato groups, and have the consequent disadvantage that they are liable to be deteriorated during storage, becoming colored and giving rise to cyclic isocyanurates, dimers, oligomers and higher polymers.

Various stabilizers for incorporation in organic isocyanates to improve stability on storage have previously been proposed, such as phenols, phosphites, acyl halides, carbon dioxide, sulfur dioxide, N,N'-disubstituted thioureas and phosphorus chlorides, but none of them has provided a satisfactory stabilization efl ect.

It has been found unexpectedly by the present inventors that the organic isocyanates can be stabilized against said unfavorable coloration and polymerization by the incorporation of a small amount of an acyl isocyanate as a stabilizer.

Therefore, it is the main object of the present invention to provide an organic isocyanate composition which is stabilized against polymerization and coloration.

Another object of the present invention is to provide a method for stabilizing an organic isocyanate against unfavorable polymerization and coloration.

Said objects are realized by incorporating into the organic isocyanate an effective amount of one or more of acyl isocyanates which are represented by the formulae:

3,743,665 Patented July 3, 1973 wherein each of X and Y is O or S, R is an alkyl, aralkyl or aryl, all of which may be substituted by one or more halogens, NO CN, alkyl or alkoxy, and R is a bivalent hydrocarbon residue.

Referring to the general formulae the alkyl group for R and the substituent thereof is exemplified by methyl, ethyl, propyl, i-propyl, butyl, s-butyl, i-butyl, t-butyl, pentyl, hexyl, dodecyl, decyl, or the like. It is preferable that the alkyl group has carbon atoms not more than 12.

The aralkyl group represented by R is exemplified by benzyl, phenethyl or the like, and preferably those having carbon atoms at most 12.

The aryl group represented by R is exemplified by phenyl, tolyl, naphthyl or the like, and, preferably those having carbon atoms not more than 10.

The alkoxy group is exemplified by methoxy, ethoxy, propoxy, i-propoxy, butoxy, s-butoxy, i-butoxy, t-butoxy, pentyloxy, hexyloxy, decyloxy, dodecyloxy, or the like. Among them, it is recommended that the alkoxy group is that of at most 12 carbon atoms.

The halogen atoms include bromine, chlorine, fluorine or the like.

The bivalent hydrocarbon residue represented by R is exemplified by methylene, ethylene, propylene, phenylene, biphenylene or the like, however, preferably those having carbon atoms not more than 12.

Among the acyl isocyanates shown by the general formulae, the commercially available or the easily preparable are, for example, acetyl isocyanate, dichloroacetyl isocyanate, trichloroacetyl isocyanate, trifluoroacetyl isocyanate, nitroacetyl isocyanate, phenylacetyl isocyanate, benzoyl isocyanate, o-chlorobenzoyl isocyanate, p-nitrobenzoyl isocyanate, thioacetyl isocyanate, thiobenzoyl isocyanate, p-chlorothiobenzoyl isocyanate, acetyl isothiocyanate, benzoyl isothiocyanate, p-cyano benzoylisocyanate, terephthaloyl diisocyanate, isophthaloyl diisocyanate, methanesulfonyl isocyanate, benzenesulfonyl isocyanate, oor p-toluenesulfonyl isocyanate, oor p-chlorobenzenesulfonyl isocyanate, p-methoxybenzoyl isocyanate or the like.

These acyl isocyanates are employed in this invention singly, in combination with one another or in combination with one or more stabilizers.

The organic isocyanates, i.e. alcoholic or phenolic ester of isocyanic acid, are usually those simple organic isocyanates in which the -NCO group is attached to a hydrocarbon residue. The hydrocarbon residue may be straight, or cyclic, aliphatic or aromatic, monoor polyvalent and may also contain inert substituent such as halogen or alkoxy. Among the organic isocyanates, the commercially available or the easily preparable ones include, for example, such monoisocyanates as methyl isocyanate, ethyl isocyanate, phenyl isocyanate, benzyl isocyanate, xylyl isocyanate, etc., such diisocyanates as 2,4- and 2,6-tolylene diisocyanates, 0-, mand p-phenylene diisocyanates, 4,4'-diphenylmethane diisocyanate, mand p-xylene w,w'-diisocyanate and a mixture of m-isomer and p-isomer, 1,10-decamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3- and 1,4-bisisocyanatomethylcyclohexane, 4,4'-biphenylene diisocyanate, 4,4'-methylene-bis(2 methylphenyl)diisocyanate, 4,4'-meth ylene-bis(2 methoxyphenyl)diisocyanate, 1,5- naphthalene diisocyanate, 4,4-diisocyanatodiphenylether, 2,2-bis(4isocyanatophenyl)-propane, etc., and such polyisocyanates as 4,4,4" triphenlymethane triisocyanate, toluene-2,4,G-triisocyanate, etc.

The organic isocyanates may be employed singly, in combination, or in a mixture of its isomers, for example, xylene w,w-diisocyanate may be any of o-, mand pisomers or a mixture of more than one of them.

The effective amount of the acyl isocyanate or acyl EXPERIMENT 1 isocyanates for stabilizing the organic isocyanates is usually about 0.001% to 1% by weight, more preferably XDI (m-isomer 70%, p-isomer 30%) prepared by first, about 0.03% to 0.2% by Weight, relative to the organic hosgenating dimethylbenzene-w,w'-diamine and then subisocyanates to be Stabilized, and Said ingredients in the 5 jecting the product to repeated fractional distillation until particular ratio are brought into an intimate contact with its hydrolyzable chlorine content reaches 0.01%, is reeach other. distilled. On the other hand, test samples of stabilizers The Organic y nates are usually prepared by alloware weighed into as many 50 cc. clear colorless bottles,

ing the corresponding amines to react with phosgene and respectively. The distilled XDI is poured in each of the are recovered from the reaction mixture by means of dis- 10 bottles and air within each bottle is replaced with nitrotillation. The incorporation of the stabilizer may be made en gas. The bottles are sealed and stored. Every week 1 to a recovered isocyanate or alternatively to said reacgram each of the samples is taken out, and is dissolved tion mixture containing thus produced organic isocyain 20 milliliters of toluene to examine the solubility of nates. In the latter case, the reaction mixture in admix- 15 each sample.

ture with the stabilizer is preferably followed by the dis- The results are as follows.

Amount of Solubility in toluene afterthe stabilizer Stabilizer (percent) 1 week 2 weeks 3 weeks 4 weeks Stabilizer of this invention:

Trichloroacetyl isocyanate 05 Clear. Trifluoroacetyl isocyanate. 05 D0. Dichloroacetyl isocyanate 0. 05 Do. Benzoyl isocyanate. 0. 05 D0. Benzenesulfonyl isocyanat 0. 05 D p-Toluenesulionyl isocyanate 0. Do. Thioacetyl isocyanate 0. 05 Do. Benzoyl isothlocyanate. 0. 05 Do. Terephthaloyl diisocyanate. 0. 05 Do. p-Cyanobenzoyl isocyanate. 0. 05 D0.

Control:

::::.:::.- After 3 days, the composition itself is turbid and gives a number of precipitates in toluene. 0. 05 Turbidity after 4 days. 0. 05 Gelation after 1 day. 0.05 Turbidity after 2 days.

Triphenyl phosphit 0. 05 Geiation after 2 days.

Phosphorous pentachlorlde. 0.05 Gelatiou... Turbidity Benzoyl chloride 0.05 Clear do Acetyiehlon'de.... 0.05 ..-.do Clear Turbidity...

Carbon dioxide.. 1 0. 1 Geiation after 2 days Sulfur dioxide--- o.1 Clear.-.... Clear Turbidity...

Phosgene 0.05 do do Clear Turbidity.-

1 Approximately. tillation so as to obtain the stabilized isocyanate com- It is also to be noted that the XDI compositions conposition containing the organic isocyanate and the stataining any of the present stabilizers can be safely stored bilizer. for a long period of time (e.g. longer than one year) Many organic isocyanates are unstable, but xylene w,w'- Without causing any polymerization or coloring.

diisocyanate (hereinafter referred to as XDI) is partic- EXPERIMENT 2 ularly unstable. For example, when the hydrolyzable chlorine content of XDI is less than 0.01 percent on XDI (m-isomer 70%, p-isomer 30%) containing 0.01 weight basis, XDI sometimes is converted into a solid 45 percent by weight of hydrolyzable chlorine shows turbidpolymer or forms a turbid liquid containing a polymer ity in relatively a short period of storage. Various staon storage for a few weeks. Even when no change in the bilizers are added to this turbid XDI. The resulting mixappearance of XDI is recognized, the formation of an tures are distilled again to give stable XDI compositions. insoluble material is observed upon adding the stored To each of these XDI compositions, 0.1% of sodium XDI into toluene. In this connection, polymerization of 0 cyanide is added and the mixture is allowed to stand XDI can be intentionally accelerated by the addition of at C. so as to see if turbidity occurs. Portions of the a small amount of sodium cyanide. XDI compositions are stored in nitrogen-filled bottles to According to the present invention, even such an XDI examine the solubility of 1 gram of each sample in containing a basic material, for example, sodium cyanide milliliters of toluene. The results are as follows.

Amount of the stabilizer Gelation by sodium Solubility in toluene after 4 Stabilizer (percent) cyanide weeks Stabilizer of this invention:

Trichloroaeetylisoeyanate 0.1 Unchanged forddays. Clear.

Trifluoroacetylisocyanate 0.1 do 1 Do.

Benzenesulfouyl isocyanate 0. 1 Slightly turbid.

Thioacetyl isocyanate 0. 1 D0.

p-Nitrobenzoyl isocyanate. 0. 1 Clear. Control:

No iliz r M Immediate gelation-.- Composition itself shows tur- Benzoyl ehioride Do.

Carbon dioxide Do.

N,N-d.ibutylthiourea Do.

or the hydrolyzable chlorine in sa1d range can be stabi- EXPERIMENT 3 v d lized remarkably. 70 4,4-d1phenylmethane dusocyanate, prepared by phos The followin ex eriments will serve to illustrate the genating p,p"methylene'dianiline q t PP Y the resent inventiogn 5 a an of usefulness and product, is distilled. At 0., the distillate 1S fractionalp p ly poured in cc. clear colorless bottles each bottles obviousness of the present invention without limiting the previously containing weighed portion of the followingv scope of this invention thereto. stabilizers.

After the air in each bottle is replaced with nitrogen which comprises incorporating into the organic isocyanate an effective amount of one or more of acyl isocyanates represented by the formulae:

R CX-NCY and RKCO-NCO);

wherein each of X and Y is O or S, R is an alkyl having Amount of the Insolubles stabilizer in toluene Stabilizer (percent) Precipitation (percent) Stabilizer of this invention;

Triehloroacetyl isocyanate 0. 01 Trifiuoroacetyl isocyanate 0. 01 Benzenesulfonyl isocyanate. 0. 01 p-Cyanobenzoyl isocyanate. 0. 01 Thioacetyl isocyanate 0. 01 Terephthaloyl diisocyanate. 0. 01 Control;

No stahiliver 0,3 Pyrogallol 0. 03 Guaieol 0. 05 Triphenyl phosphite 1. Phosphorus pentachloride 0.05 Benzoyl chloride. 0.05 Acetyl chloride. 0. Phosgene 0. 07 Carbon dioxide 0. 8 Sulfur dioxide 0. 2 N ,N-dibutylthiou.rea 0. 76

What is claimed is:

1. A stabilized organic isocyanate composition comprising, as the main component, an organic isocyanate, in an intimate admixture with one or more of acyl isocyanates which are represented by the formulae:

wherein each of X and Y is O or S, R is an alkyl having not more than 12 carbon atoms, aralkyl having at most 12 carbon atoms, aryl having not more than 10 carbon atoms, all of which may be substituted by one or more halogens, -NO --CN, or alkoxy having at most 12 carbon atoms, and R is phenylene, and the amount of the acyl isocyanate or acyl isocyanates being about 0.001 to 1.0 percent by weight relative to the organic isocyanate contained.

2. A composition as claimed in claim 1, wherein the acyl isocyanate is trichloroacetyl isocyanate.

3. A composition as claimed in claim 1, wherein the acyl isocyanate is trifluoroacetyl isocyanate.

not more than 12 carbon atoms, aralkyl having at most 12 carbon atoms, or aryl having not more than 10 carbon atoms, all of which may be substituted by one or more halogens, -NO ON, or alkoxy having at most 12 carbon atoms, and R is phenylene.

10. A method as claimed in claim 9 ,wherein the amount of the acyl isocyanate or acyl isocyanates is about 0.001% to 1% by weight relative to the organic isocyanate.

11. A method as claimed in claim 9, wherein the acyl isocyanate is trichloroacetyl isocyanate.

12. A method as claimed in claim 9, wherein the acyl isocyanate is trifiuoroacetyl isocyanate.

13. A method as claimed in claim 9, wherein the acyl isocyanate is benzoyl isocyanate.

14. A method as claimed in claim 9, wherein the acyl isocyanate is benzoyl isothiocyanate.

15. -A method as claimed in claim 9, wherein the acyl isocyanate is p-nitrobenzoyl isocyanate.

16. A method as claimed in claim 9, wherein the acyl 4. A composition as claimed in claim 1, wherein the isocyanate is p-cyanobenzoyl isocyanate.

acyl isocyanate is benzoyl isocyanate.

5. A composition as claimed in claim 1, wherein the acyl isocyanate is benzoyl isothiocyanate.

6. A composition as claimed in claim 1, wherein the acyl isocyanate is p-nitrobenzoyl isocyanate.

7. A composition as claimed in claim 1, wherein the acyl isocyanate is p-cyanobenzoyl isocyanate.

8. A composition as claimed in claim 1, wherein the acyl isocyanate is terephthaloyl diisocyanate.

9. A method for stabilizing an organic isocyanate,

17. A method as claimed in claim 9, wherein the acyl isocyanate is terephthaloyl diisocyanate.

References Cited UNITED STATES PATENTS 3,330,849 7/1967 Ulrich 260-453 LEWIS GO'ITS, Primary Examiner D. H. TORRENOE, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 743 665 Dated Jul 3 1973 Kenji Naito, Katsuhiko Ogino, Hiroshi Okudo,

lnventofls) Michio Tanaka, Yoshio Kamatani Hiroshi Mukai Tatsuro Takeuchi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, between lines 6 and 7, under the title, please insert the following: Claims priority, application Japan, June ZO, 1969,

Serial No. 48748/1969 Signed and sealed this 18th day of December 1973. I

(SEAL) Attest:

EDWARD M. FLETCHER, JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents 

